<title>Dynamics of raindrop size distribution from the data of high-frequency Doppler sodar measurements</title>

Abstract

A new method has been suggested for reconstruction of raindrop size distribution and ram intensity from the normalized spectra of acoustic signals measured with a cw bistatic Doppler sodar. A data processing algorithm has been constructed and successively used for real sodar data processing based on the analytical formulas derived in the Rayleigh approximation and with the use of the exact Mie formulas. The raindrop size spectra were reconstructed from the individual power spectra of signals recorded every 20 s and from the signal power spectra averaged over 2-, 3-, 5-, and 25-nun periods. This has allowed us to track the dynamics of the raindrop size distribution. The presence of the second maximum of the number density of large raindrops was established, whose position shifted with time from 0.3 to 1 mm. Our study has shown that the large raindrops were grouped in ensembles and the second maximum of raindrop size distribution was observed only periodically. The obtained results demonstrate that high-frequency cw bistatic sodars are very promising for measurements of ram.

<title>Minisodar for atmospheric investigations</title>

“…In particular, higher frequencies of acoustic remote sensing, in addition to measurements of the meteorological and turbulent characteristics of the atmosphere based on the effect of acoustic wave scattering by the atmospheric turbulence, allow the quantitative characteristics of hydrometeors to be measured [2]. They have been developed intensively in the last few years and have occupied their own specific place in studies of the lower layer of the atmosphere because of higher spatiotemporal resolution and some other capabilities.…”

“…Sufficiently high spectral resolution enables the selection of contributions from droplets of different sizes [2].…”